In electronics systems, electronic components such as printed circuit boards are often housed in modules having holes in their top and bottom portions to allow for air circulation through the components for cooling purposes. The modules tend to be arranged vertically, side-by-side and housed within a cabinet or chassis.
Typically, the cooling air is provided by fans which are placed in a permanent, fixed location inside the cabinet.
Traditionally the system is made non-redundant for cooling. In other words, if any of the fans in the system fails, the system must shut down. For example, if the system relies upon two fans, and one fan fails, then in a typical system, the remaining fan is unable to create sufficient airflow through the entire electronics system to adequately cool the entire system. The insufficiently heated portion of the system will burn out if the system is not shut down.
Some systems are made redundant for cooling. In other words, the system can continue to operate even if one fan fails. In such redundant systems, the airflow throughout the system is maintained above a minimum flow rate in order to keep any part of the system from over-heating. One method for creating a redundant system is to add more fans. However, the addition of fans increases the cost of the system and may not be possible or practical where space is limited.
The prior art reveals complicated techniques to help improve the evenness of airflow through electronics systems. For example, UK patent application 2,197,536, in the name of STC plc and published on May 18, 1988, describes an equipment cabinet having a central chimney or spine in the centre, surrounded by electronic circuit units. The units are stacked vertically. By a complicated arrangement of air intake areas, baffles, and inlets into the chimney, the cabinet helps to evenly distribute airflow through the units. However, this invention requires a specially built cabinet and chimney structure and requires the ability to stack electronic component units vertically, which, given space constraints may not be possible or desirable in many electronics systems.
A simpler device for improving airflow through electronic modules is described in U.S. Pat. No. 4,860,163 which was issued to Sarath on Aug. 22, 1989. The Sarath device describes a cabinet for holding circuit board modules, with a fan drawing air at one end of the cabinet. There is a wall at the end of the modules closest to the fan preventing air from flowing directly from the modules to the fan. Instead, air must flow out the side of the modules and around the wall to reach the fan. To prevent air from simply flowing out the side of the modules without flowing over the surface of the modules, baffles are placed along a portion of the sides of the modules to force air to flow over at least a portion of the modules. While this device does cause air to flow over some portion of the modules, it does not cause air to flow evenly over all areas of the modules, which may lead to uneven cooling.